Calibre stores all books and its database in one directory (ususally called
CalibreLibrary in your home directory). To access your collection of
electronic books from everywhere, especially with your reading and mobile
devices, synchronize this directory with ownCloud Desktop Client.

The good news is, you can remove DRM from your eBooks. There is a plugin for
Calibre, the eBook library application, which once installed, will do this
automatically with every eBook you add to your Calibre library.

The bad news is, its a bit complicated to setup:

We use Calibre under Linux, but the Adobe DRM stuff runs under Windows only. To
run windows programs in Linux, the Windows emulation software called wine is
used.

The scripts who do the magic of releasing your eBooks from DRM are Python
scripts. As those Python scripts must access the Adobe Digital stuff, they also
have to be run in the same emulated Windows environment. Therefore our wine
environment needs to be able to run Python scripts. A Python-version for Windows
must therefore be installed under the wine environment.

DRM is done by encrypting the media-content and decrypting it only for
authorized access. The scripts use Python modules for cryptography, which also
must be installed under the wine environment.